Is lowering amplitude or bandwidth more effective in controlling treatment-emergent central sleep apnea after Inspire (Upper Airway Stimulation) therapy?

Managing Treatment-Emergent Central Sleep Apnea After Inspire Therapy

Lowering amplitude is more effective than adjusting bandwidth for controlling treatment-emergent central sleep apnea (TECSA) after Inspire therapy.

Understanding Treatment-Emergent Central Sleep Apnea

Treatment-emergent central sleep apnea (TECSA) is a phenomenon where central apneas develop during treatment of obstructive sleep apnea (OSA). While commonly associated with CPAP therapy, TECSA can also occur with hypoglossal nerve stimulation (Inspire therapy) 1.

Key characteristics of TECSA include:

• Emergence of central events during treatment of primary OSA
• Often occurs at higher treatment settings
• May be transient in many cases

Pathophysiological Mechanisms

TECSA after Inspire therapy likely shares similar mechanisms with TECSA observed in other treatment modalities:

• Ventilatory control instability: Higher stimulation voltages may lead to increased ventilatory drive and subsequent hypocapnia 1, 2
• Overcorrection: Excessive stimulation may eliminate upper airway obstruction but disrupt normal breathing patterns
• Sleep state transitions: Arousals from sleep can trigger central events 3

Evidence for Amplitude Reduction

Recent evidence demonstrates that reducing stimulation amplitude (voltage) is the most effective approach for managing TECSA with Inspire therapy:

• Case reports show that central apneas emerge at higher voltages during hypoglossal nerve stimulator titration 1
• Central apneas resolve when patients are maintained at stable, lower voltages 1
• When patients are trialed at higher voltages again, central apneas can recur 1

This pattern mirrors findings from CPAP-related TECSA studies, where reducing inspiratory pressure (IPAP) has been shown to resolve central events 4. In one study, reducing IPAP resulted in complete resolution of TECSA in all patients with adequate sleep data, with central apnea index decreasing from 17.3 ± 11.0 to 1.5 ± 1.7 events/h (P < .001) 4.

Management Algorithm for TECSA After Inspire Therapy

1. Identify TECSA during titration:

   • Document emergence of central events at specific voltage settings
   • Confirm absence of other causes of central apnea (heart failure, medications)

2. Adjust stimulation parameters:

   • First-line approach: Reduce amplitude (voltage) by 0.5-1V increments until central events resolve while maintaining adequate OSA control 1
   • Second-line approach: If amplitude reduction compromises OSA control, consider adjusting bandwidth

3. Follow-up monitoring:

   • Schedule follow-up sleep study to confirm resolution of TECSA
   • Monitor for symptom recurrence or inadequate OSA control

Special Considerations

• Transient nature: Like CPAP-related TECSA, some cases may resolve spontaneously with continued therapy at stable settings 1, 2
• Persistent cases: For persistent TECSA despite amplitude adjustments, consider:
  • Evaluation for underlying medical conditions (heart failure, medication effects)
  • Alternative OSA treatments if Inspire therapy cannot be optimized

Pitfalls to Avoid

• Excessive voltage reduction: Reducing amplitude too much may compromise OSA control
• Ignoring TECSA: Untreated central apneas may contribute to persistent symptoms and reduced therapy adherence
• Overlooking medical comorbidities: Heart failure and certain medications can exacerbate central sleep apnea 3

While clinical guidelines specifically addressing TECSA with Inspire therapy are limited, the approach of reducing stimulation amplitude aligns with the established principle of reducing inspiratory pressure in CPAP-related TECSA 3, 4.